TomR

Posted 01 December 2006 - 02:39 AM

Hello -
Any suggestions on how, exactly, to accomplish a texture substitution as described below by T. Patterson?

From Tom Patterson's "Getting Real: Reflecting on the New Look of National Park Service Maps", 2002

"Using an aerial photograph or satellite image (registered to a base map), land cover is carefully delineated as Photoshop selections with pixel-level precision. These selections are then transferred to the base map, where they are filled with generic land cover textures cloned from the aerial photograph, or even from other photographs (Figure 9)."

Mike H

Posted 01 December 2006 - 01:40 PM

Texture mapping (also called bump-mapping) can be achieved several ways. Patterson is presenting the concept as art more than an instructional technique.

The general workflow is to compile whatever raster images you have of a region, ideally as registered layers in photoshop. From there a process of experimentation ensues, where you can select areas using Photoshops many tools, and build masks, cut and paste, emboss, engage opacity effects, and flatten - eventually creating the aestehtic look and feel you desire.

Looking at his graphic examples, he selected the pink pixels around Fox River. Then he pasted them on a new layer and made them green. He may have embossed (filter) them a little to produce the texture (bumps). Then he merged (flattened) them on the otherwise smooth surface of the grayscale DEM, effectively conveying a strong visual sense of deciduous forest.

He did so for each individual pixel color afforded by the ERDAS data, and it appears he simplified 18 classifications into a matrix of 5 coarse categories.

As you can imagine, this "experimentation" represents much trial and error... there is no easy step-by-step process. Additionally, the map scale and available data will determine the limitations of experimentation. But combined with the vision that Patterson offers, you can produce stunning results if the data allows it.

Thanks for the suggestions. Tried using the watercolor filter on a 1m-resolution USGS DOQ, then the emboss filter in PS CS, with okay results. Any tips on creating "land cover textures", using Patterson's terminology, from DOQ-forest cover images? Cheers,TomR----Bellingham, WA

This was a grayscale DOQ base, and by selecting pixels in photoshop we separated forest from urban reasonably well, and tinted them green or brown accordingly. The polygons for public land use a transparent green to highlight them. On this map I didn't add texture, although it would be easy to do using emboss or any other filter.

Nat Case showed me a map at NACIS he did along these lines as well. The grayscale DOQs are pretty easy to manipulate once you get a sense of the selection thresholds in Photoshop.